When running, an automotive internal combustion engine normally produces vapour (or so-called “blowby gas”) in the cylinder heads and/or oil tank. Since air pollution regulations prohibit exhaust of such vapour into the atmosphere, and require that it be fed into the cylinders for controlled combustion, internal combustion engines are equipped with a recirculating circuit comprising a feed pipe fitted to the cylinder head or oil tank and connected to an intake pipe of the engine.
During routine servicing of the engine, the feed pipe may be disconnected from the intake pipe and/or cylinder head for cleaning or replacement, or simply to permit easy access to other parts of the engine, and, once disconnected from the intake pipe and/or cylinder head, may be reconnected poorly due to carelessness on the part of the fitter. Since such a situation easily goes undetected, by the vapour being released directly into the atmosphere and in no way impairing operation of the engine, more recent air pollution regulations require correct connection control of the feed pipe, and that the driver be alerted of any faulty connection.
One solution to determine correct connection of the feed pipe is described in Patent U.S. Pat. No. 6,532,931-B1, in which the feed pipe is provided on the ends with connecting devices, each of which comprises a pneumatic connector for pneumatically connecting the feed pipe to the intake pipe or cylinder head; and an electric connector. Each connecting device is designed so that the relative pneumatic connector is only connected to a corresponding pneumatic connector on the intake pipe or cylinder head when the relative electric connector is connected to a corresponding electric connector on the intake pipe or cylinder head. Consequently, correct connection of the pneumatic connectors, and therefore of the feed pipe, can be determined by determining the electric continuity of the circuit formed by connection of the electric connectors.
The connection system described in Patent U.S. Pat. No. 6,532,931-B1, however, has several drawbacks by employing connecting devices comprising a pneumatic connector and an electric connector in the same structure, which makes thorough cleaning of the pneumatic connector problematic. Moreover, any change in the diameter of the pneumatic connector involves high-cost alteration of the connecting device as a whole.